The present invention relates to a cylinder head apparatus of an internal combustion engine for vehicles and particularly to a cylinder head apparatus, which possesses an opening for returning the oil of the valve chamber of a cylinder head to an oil pan through a chain case.
As an example of a cylinder head apparatus for an internal combustion engine, it is disclosed in Japan Laid-Open Patent 2000-97103. In the cylinder head apparatus, the oil which collects in the valve chamber of the cylinder head is discharged into the chain case through the opening, which is placed on the mounting surface of the chain case. The oil is dropped into the chain case, continuously guided to an oil pan.
In the chain case mounted on its mounting surface of the cylinder head and the cylinder block, a timing chain which connects a crankshaft and a camshaft is provided. Also a tensioner for adjusting the tension of the timing chain and a chain guide for guiding the timing chain are often prepared in the chain case. When such tensioner and chain guide are employed, oil must be supplied to the sliding portions of the tensioner and the chain guide for lubrication.
However, there has existed a problem that a special lubricating oil pathxe2x80x94which is for supplying the oil to the sliding portions of the tensioner and the chain guidexe2x80x94renders the cylinder head too bulky.
The object of the present invention is to facilitate an appropriate oil supply to the sliding portions of the tensioner and the chain guide while obviating the accompanying need for the bulkiness of the cylinder head.
The present invention to solve the problem mentioned above provides a cylinder head apparatus comprising: a cylinder head connected to a cylinder block; a valve chamber which is formed in the cylinder head; a chain case provided on the side of the cylinder block; and an opening which is provided on a mounting surface of the chain case for discharging an oil of the valve chamber into the chain case, wherein a timing chain and at least either a tensioner for applying tension to the timing chain or a chain guide for guiding the timing chain are disposed on the mounting surface of the chain case of the cylinder block inside the chain case, and wherein an oil dropping rib for guiding the oil, which is discharged through the opening, to a sliding portion of the tensioner or the chain guide is provided on the mounting surface of the chain case.
The invention employs the oil dropping rib for guiding the oilxe2x80x94which is discharged through the openingxe2x80x94to the sliding portion of the tensioner which is for applying the tension to the timing chain, or of the chain guide which is for guiding the timing chain. The oil discharged from the valve chamber can thus be efficiently used in order to lubricate the sliding portion of the tensioner or the chain guide. Therefore, an appropriate oil supply to the sliding portion of the tensioner or the chain guide can be attained without preparing a special lubricating oil path for the cylinder head.
The invention provides the cylinder head apparatus wherein the opening is formed on a boss projecting from the mounting surface of the chain case of the cylinder head, and the oil dropping rib is connected to be flush with the boss.
The invention employs the opening for discharging the oil, which is formed on the boss projecting from the mounting surface of the chain case of the cylinder head. The boss is flush with the oil dropping rib. The oil discharged through the opening will travel straight to the oil dropping rib and reach the tensioner guided by the oil dropping rib. Therefore, the oil discharged through the opening can be guided to the tensioner securely.
The reduction in the stiffness of the cylinder head due to providing an opening thereon is restrained since the opening is formed on the boss.
The invention provides the cylinder head apparatus wherein the oil dropping rib is connected to a plurality of connecting ribs, which interconnect a plurality of mounting bosses and are provided on the cylinder head.
The invention provides the cylinder head apparatus wherein the oil dropping rib is connected to the plurality of connecting ribs, which interconnect the plurality of mounting bosses and are provided on the cylinder head.
In the invention the oil dropping rib is connected to the connecting ribs which interconnect the bosses, thereby increasing the stiffness of the cylinder head.
The resultant stiffness of the chain case can also be increased by connecting a plurality of the bosses.